Rotation mechanism for rock drills



Nov. 12, 1940. W. A. SMITH, JR 2,221,117

RoTATIoN MECHANISM FOR Rocx DRILLs Filed June 5o, 1938 INVENTOR W/LL/A/V A. SIW/777; Je.

Y ATTORNEY Patented Nov. 12, 1940 UNITED STATES vraars-1v1 ortica Application June 30, 1938, `Serial No. 216,659

4 Claims.

This invention relates broadly to rock drills, but more particularly to a mechanism for rotating the drill steel.

One object of this invention is to provide a rotation mechanism for rock drills with a clutch automatically releasable for rendering said mechanism inoperative when the drill steel normally rotated thereby is subjected to an abnormal resistance, the clutch being automatically reengageable after release.

Other objects of this invention will be apparent fromV the .following detailed description whereinsimilar characters of reference designate corresponding parts and wherein:

Fig. 1 is a longitudinal sectional view of the upper end of a rock drill embodying the inven tion.

Fig. 2 is a cross sectional view taken in a pian indicated by line 2-2 in Fig. 1.

Fig. 3 isa cross sectionalview taken in a plane indicated by line 3-3 in Fig. 1.

Fig. 4 is a view similar to Fig. 1 showing a modication of the invention, and

Fig. 5 is a longitudinal sectional view taken in a plane indicated by line 5-5 in Fig. 4.

Referring tothe drawing, III represents the cylinder-of the rock drill having a piston II reciprocable therein by motive uid alternatively admitted into both endsv of the cylinder. 'Ihe upper end of `the cylinder I0 is enlarged to formk a counterbore I2 of a diameter equal to that of another counterbore I3 formed within a back head I4 which is coaxially secured above the cylinder by side bolts I5. Resting on the bottom of the counterbore I2, there is a bearing plate I6 supporting the head I'| of a riiie bar I8, which bar extends through the plate I6 into the piston II where it is operatively associated with a rifle nut (not shown). The head I'| is adequately n machined to pivotally receive two or morepawls I9 constantly urged outwardly by spring pressed plungers 20. Also supported by the bearing plate I6, and extending therefrom to the bottom of the counterbore I3, there is a sleeve or ratchet 5 ring 2| capable of rotation within a hardened bushing 22 clamped between the bottom of the counterbore I3 and the bearing plate I6. For a portion of its length equal to the length of the head of the rifle bar IB, the ring 2| is formed with internal teeth 23 surrounding the head I1 and engageable by the pawls I9.

Above the teeth 23, the ring 2| is enlarged to form a smooth counterbore 24 having mounted therein the lower end portion of a stationary cap or locking member 25 held against rotation relative to the back head Ill by any suitable means such as a key 26. The cap 25 is internally threaded as at 21 to receive a removable plug 28 by which a tube 29 is held in position, which tube extends through the cap 25 and the rifle bar I8 for conveying cleansing uid such as compressed air or water to the drill steel.

Within the lower end portion of the capi 25, there are two diametrically disposed radially eX- tending bores 30, each having slid'able therein a 10 seat or .washer 3| formed with a socket 32 accommodating a ball 33, which ball is urged outwardly by a spring 34 acting on the washer 32. Adjacent-the balls 33, the ring 2| is provided with two diametrically disposed radial holes 35 oi a 15 diameter somewhat smaller than that of the balls and forming within the counterbore 2A notches adapted to receive the balls for releasably locking the ring 2| to the stationary cap 25.

In the modification shown in Fig. 4, the balls 20 are replaced by plungers 36 slidable within the bores SIL-each having its outer end wall shaped with a cross rib 31 of semi-circular cross section, which rib is engageable with the side walls of one or the other of two V-'shapedv grooves 38 cutv inV 25 the inner wall of the counterbore 24 and eX- tending longitudinally thereof.

The operation of the mechanism is as follows: During the forward or working strokes of the piston I I Within the cylinder lil, the rirle bar I8, 30 due to its operative association with the piston, will rotate in a counterclockwise direction in Fig.

3, which rotation is not prevented by the engagement of the pawls I9 with the teeth 23. After the piston has delivered its blow to the drill steel, it 35 will start in its return stroke, that is toward the bearing plate I5. During this return stroke, the piston II, due to its operative engagement with the rifle bar I8, will impart a torque to the ba-r I8 in a clockwise direction in Fig. 3. In this in- 40 stance, the pawls I9 engaging the teeth 23 will prevent rotation of the bar in a clockwise direction, consequently causing the piston II to rotate in a counterclockwise direction, whichrotation is transmitted to the drill steel by any 454 suitable chuck well known in this art.

To enable this rotation of the piston and the consequential rotation of the drill steel in one direction, it will be understood that the rifle bar I8 must be locked against rotation in one direction. This lock is accomplished by the pawls I9 engaging the teeth 23 of the ratchet ring 2|, which ring is normally held against rotation by the clutch including the spring loaded balls 33 held under pressure in the notches formed in the ring by the holes 35. When the piston Il is subjected to a predetermined or abnormal resistance to rotation such as resulting from the binding of the drill steel in the ground, it will transmit to the rifle bar I8 an additional torque which will inturn be transmitted to the ring 2l by the pawls i9. In this instance, the notches 35 engaged by the balls 33 will exert suiicient pressure on the balls for driving them into the bores 30 against the eiort of the springs 34, thereby enabling a momentary rotation of the ring 2| and a return stroke of the piston H Without rotation. 'I'his rotation of the ring will continue during each return stroke of the piston until the drill steel, vibrated by the impacts of the piston thereon, is released from its binding condition. Thereafter, the balls 33 dropping intoy the notches 35 will create sufficient friction between the ring 2 l. and the cap 25 to overcome the torque to which the ring is subjected, and will lock the ring against further rotation for enabling the piston to resume its rotation during its return strokes, which rotation is again transmitted to the drill steel.

In the modification shown in Figs. 4 and 5, the rib 37 of each plunger 36 engaging the side walls of the corresponding V-shaped groove 38, will normally hold the ring against rotation. However, when the ring is subjected to an abnormal torque, the side Walls of the grooves 38 will exert suicient pressure on the plunger 36 to release the ring, and thereafter be reengaged by the plungers 35 to again lock the ring against rotation in the manner above described.

In practice, the springs 34 are made in a manner calculated to enable release of the clutch between the ring 2l and the cap 25 prior to the stalling of the piston l l Within the cylinder ID, which stalling would otherwise take place when `the action lof the motive fluid-on the piston is not sucient to overcome the torque resistance to which the drill steel may be subjected. In the case of a hand held rock drill, the springs 34 are made to cause release of the clutch at a time when the torque transmitted to back head I4 may still u be `comfortably resisted by the operator holding the rock drill, thereby overcoming the possibility of subjecting the operator to an excessive fatigue and facilitating operation of the drill.

I claim:

l. In a rock drill, the combination with a cylinder and a reciprocatory piston in the cylinder, of a ratchet mechanism operatively associated with the piston responsive to its reciprocation for normally electing its rotation, said mechanism including a rotatable ratchet ring, a stationary locking member internally of said ratchet ring, notches on said ring, and spring loaded detents carried by said member normally engaging said notches for preventing rotation of said ring, thel interengaging surfaces of said notches and detents being shaped and disposed in a manner eiecting inward movement of said detents out of said notches upon a predetermined resistance to rotationY of4 said piston to enable rotation of said rmg.

2. In a rock drill, the combination With a cylinder and a reciprocatory piston in the cylinder, of a ratchet mechanism operatively associated with the piston responsive to its reciprocation for normally effecting its rotation, said mechanism including a rotatable ratchet ring formed with a sleevelike extension, a stationary member Within the extension of said ring, notches on the inner surface of said extension, spring loaded detents carried by said stationary member normally engaging said notches for preventing rotation of said ring, and means responsive to a predetermined resistance to rotation of said piston for effecting inward release movement of said detents to enable rotation of said ring.

3. In a rock drill, the combination with a cylinder and a reciprocatory piston in the cylinder, of a ratchet mechanism operatively associated with the piston responsive to its reciprocation for normally effecting its rotation, said mechanism including a rotatable ratchet ring, notches on the inner surface of said ring, and spring loaded detents within said ring held against rotation with the ring, said detents normally engaging said notches for preventing rotation of said ring and being capable of inward release movement relative to the ring to enable said rotation.

4. In a rock drill, the combination with a cylinder and a reciprocatory piston in the cylinder, of a ratchet mechanism operatively associated with the piston responsive to its reciprocation for normally effecting its rotation, said mechanism including a rotatable ratchet ring, notches on the inner surface of said ring, detents Within said ring held against rotation therewith, and means active on said detents for effecting their operative engagement with said notches to prevent rotation of said ring during certain conditions of operation and enabling inward release movement of the detents to enable said rotation during other conditions of operation.

WILLIAM A. SMITH, JR. 

